Cardiovascular disease is a serious illness and cardiac electrophysiological signals (such as signal magnitude) are utilized to diagnose and characterize associated patient electrophysiological (EP) pathology, such as atrial fibrillation and myocardial ischemia (MI). Usually, surface ECG signal and intra-cardiac EP signal analysis based on waveform morphology and time domain parameters is utilized for cardiac arrhythmia detection and characterization as well as determination of P wave morphology changes, R-R wave time intervals and heart rate variability analysis. Some known systems employ tissue impedance based analysis and diagnosis based on temperature measurement in an ablation procedure for cardiac arrhythmia discrimination (using a thermistor), for example. However, known systems typically focus on calculation and interpretation of a single EP impedance derived in response to an external stimulation pulse. Such stimulation involves generation of electrical noise that degrades EP signals and involves current, voltage and power leakage that may impair patient safety and may degrade precision and reliability of impedance measurement and analysis.
Known signal processing systems use intra-cardiac electrograms to analyze cardiac arrhythmias, such as Atrial Fibrillation (AF) and Ventricular Fibrillation (VF), but these systems fail to determine intrinsic electrophysiological characteristics of heart tissue for more accurate and reliable diagnosis of cardiac arrhythmia, such as impedance. Known cardiac tissue or body impedance measurement systems for cardiac function diagnosis and evaluation fail to comprehensively determine tissue impedance, especially impedance changes and fail to identify cardiac disease and severity. In cardiac impedance analysis, electrophysiological signals (such as surface ECG signals, ICEG (intra-cardiac electrogram) signals) and vital signs (pressure signals, respiration signals) are typically inadequately used in impedance estimation and quantification. A system according to invention principles addresses these deficiencies and related problems.